Effects of antireflux therapies on salivary function in normal humans

Saliva has received recent attention because of its potential role in esophageal clearance and neutralization of refluxed gastric contents. Gastric antisecretory drugs or promotility drugs used to treat reflux have not been studied for their ability to affect salivary function. We conducted a double-blind randomized study of four antisecretory drugs, two promotility drugs, and placebo (PL) on 12 healthy volunteers on seven different days. Following a 6-hr fast, accumulated saliva was expectorated at least once per minute. The initial 10-min sample was discarded and a baseline 20-min sample collected. One of the following was given per os: PL, pirenzepine (PIR), 50 mg; propantheline (PRO), 30 mg; cimetidine (CIM), 300 mg; ranitidine (RAN), 150 mg; bethanechol (BET), 25 mg; or metoclopramide (MET), 10 mg. Saliva was collected for 60 min. Saliva was then stimulated (STIM) by sucking a peppermint lozenge for 30 min. Specimens were collected under oil, kept on ice, and analyzed within 30 min. Saliva flow in milliliters per minute and capacity for acid neutralization (CAN) in microequivalents acid per milliliter saliva were analyzed on all samples. The known effect of PRO to inhibit both basal saliva flow and STIM flow and CAN was seen. In contrast, the selective antimuscarinic PIR did not significantly decrease saliva flow or CAN. CIM, RAN, and MET did not significantly effect salivary function, but both CIM and RAN showed a tendency to increase CAN. Oral BET had no detectable effect on salivary function.